1 . Field of the Invention
The present invention relates to a device and a method for testing disconnection of bus lines of a semiconductor device. More particularly, it relates to a device and a method for testing disconnection by grouping bus lines of a semiconductor device to find disconnected bus lines by grouping by n units bus lines to which switching devices whose current ratios from a geometric series are connected and measuring a sum of the current flowing through the bus lines grouped by n units when testing disconnection of a semiconductor device having bus lines as dynamic random access memory (DRAM), static random access memory (SRAM), liquid crystal display panel and the like.
2. Description of the Prior Art
Tests of disconnection or short of bus lines are performed when manufacturing semiconductor devices having bus lines (or electrode lines) as DRAM, SRAM, liquid crystal display panel, and the like.
FIG. 3 is a circuit diagram showing a method for testing disconnection of bus lines of a semiconductor device according to a conventional art.
A liquid crystal panel 30 is shown in FIG. 3, and there are formed electrodes DPAD, GPAD for applying test voltage respectively on an upper area in a column and on a left side in a row, and electrodes D1 to Dj and G1 to Gi for detecting current respectively on a lower area in a column and on a right side in a row.
The test determining whether the bus lines of the liquid crystal panel 30 are disconnected or not is performed by applying test voltage to the electrodes DPAD and GPAD on the upper area and the left side of the liquid crystal display panel 30, and testing whether the current is detected or not from the electrodes G1 to Gi and D1 to Dj on the lower area and the right side.
However, according to the conventional art, since each bus line of the semiconductor should have one testing electrode although the number of bus lines increases, spaces between the bus lines narrow, and whereby the bus lines have high density, the testing time increases and it becomes difficult to test minutely. Such a problem is more serious in a liquid crystal display panel that has a plurality of bus lines.
Korean Patent Publication Nos. 93-3670, 93-3672, and 93-7162 provide respectively a device for testing an indium tin oxide (ITO) electrode of a flat panel device, a method and a device for testing disconnection-short of a transparent electrode of a liquid crystal display device, and a device and a method for testing a transparent electrode of a flat panel device.
According to the above techniques, a micro processor determines whether bus lines are disconnected (or shorted) or not by current level of the bus lines (or electrode lines) of the semiconductor to which a voltage is applied. The current level is detected automatically by a switching method.
Although the current level is detected automatically by a switching method, a detection of the current level should be made one by one from each bus line. Such inconvenience and prolongation of testing time are still remaining unsolved.